Learn Hardcore Indonesian: Guru menilai tugas berdasarkan bukti di dokumen penting. - The teacher evaluates the assignment based on the evidence in the important document.

guru by itself can mean “a teacher” or “the teacher”, depending only on context.
If the speaker and listener already know which teacher is being discussed, you’d translate it as “the teacher”.
If it’s just any teacher in general, you’d translate it as “a teacher”.

To be more specific, Indonesians can add:

guru itu = that / the teacher
seorang guru = a (single) teacher

But plain guru is flexible and doesn’t mark definiteness the way English does.

What exactly does menilai mean, and how is it different from nilai and penilaian?

nilai (noun) = value, score, grade (e.g. nilai ujian = exam score)
menilai (verb) = to assess, to evaluate, to grade
penilaian (noun) = assessment, evaluation

In the sentence:

Guru menilai tugas...
→ The teacher assesses / grades the assignment...

Grammatically, menilai is meN- + nilai, forming an active transitive verb: someone menilai something.

Is tugas here “task”, “assignment”, or “homework”? How do I know which one to use in English?

tugas is a general word for task / duty / assignment. In an education context, it often corresponds to:

assignment
homework
classwork / project, depending on context

So in this sentence, natural translations are:

The teacher assesses the assignment...
The teacher grades the homework...

The Indonesian word itself doesn’t force one of those; you choose the best English word for the context.

How does berdasarkan work here? Is it always used like “based on” in English?

Yes, berdasarkan is very close in meaning and usage to “based on”.

Structure:

[Subject] + [Verb] + [Object] + berdasarkan + [Noun Phrase]
Guru menilai tugas berdasarkan bukti...
→ The teacher assesses the assignment based on evidence...

You can use berdasarkan with:

berdasarkan data = based on data
berdasarkan pengalaman = based on experience
berdasarkan peraturan = based on regulations

It always introduces the basis / grounds / source for the action.

Why is it bukti and not buktinya? What’s the difference?

bukti = evidence / proof (general, non-specific)
buktinya = the evidence, its evidence, that evidence (more specific, pointing to particular evidence)

In this sentence:

berdasarkan bukti = based on (some) evidence
– general, not highlighting which exact evidence
berdasarkan buktinya = based on the evidence (that we both know about / that has been mentioned)

Both are grammatically correct; the original uses bukti in a general sense.

Why is it di dokumen penting and not pada dokumen penting or dalam dokumen penting? Are they different?

All three can appear in similar contexts, but they have slightly different typical uses and feels:

di dokumen penting
- Literally “at/in important documents”
- Very common in everyday speech; di is the default location preposition.
dalam dokumen penting
- Emphasizes inside the documents, like “inside the important documents”
- Slightly more formal or precise.
pada dokumen penting
- More formal/literary; often used in legal/official style
- Can feel a bit stiff in casual speech.

In this sentence, di dokumen penting is natural and colloquial. dalam dokumen penting would also sound fine, with a bit more emphasis on “within”.

Is dokumen penting “an important document” or “important documents”? There’s no plural -s—how do we know?

Indonesian usually does not mark plural on nouns. dokumen penting can mean:

an important document
the important document
important documents

The number is inferred from context.

If you really need to show plurality, you can say:

dokumen-dokumen penting = important documents (explicitly plural)
beberapa dokumen penting = several important documents

The original sentence is neutral; you choose the best English number for the context.

Why is it dokumen penting and not dokumen yang penting? What’s the difference?

Both are possible, but there is a nuance:

dokumen penting
- pening is a simple adjective modifying dokumen
- Means “important documents” (as a general description).
dokumen yang penting
- Literally “documents that are important”
- Slightly more emphasized or contrastive, like “the documents that are (actually) important” as opposed to others.

In most cases, when you just want to say “important documents”, dokumen penting is more natural and concise.

The English translation has “assesses” in the present tense. How do we know the tense in Indonesian if menilai never changes form?

Indonesian verbs do not change form for tense (past, present, future). menilai can mean:

assesses / is assessing (present)
assessed / was assessing (past)
will assess / is going to assess (future)

The time is understood from context or from extra time words:

kemarin guru menilai tugas = yesterday the teacher assessed the assignment
besok guru akan menilai tugas = tomorrow the teacher will assess the assignment

In the standalone sentence, English usually defaults to present simple: “The teacher assesses the assignment...”

Can we put berdasarkan bukti di dokumen penting at the beginning of the sentence? Would that change the meaning?

Yes, you can front the phrase to emphasize the basis of the assessment:

Berdasarkan bukti di dokumen penting, guru menilai tugas.

Meaning stays essentially the same:

Based on evidence in important documents, the teacher assesses the assignment.

The difference is mainly in focus: the fronted version highlights the basis (the evidence) first. Word order in Indonesian is fairly flexible for information focus, as long as the internal order of each phrase remains correct.

What are the word parts in berdasarkan? Is it related to dasar?

Yes. berdasarkan is built from:

dasar = base, foundation, basis
ber- ... -kan around dasar, forming berdasarkan

So literally it’s something like “to have basis on / to be based on”, which matches the meaning “based on / on the basis of”.

Could I say Guru menilai tugas dari bukti di dokumen penting instead of berdasarkan?

You can, but the nuance changes slightly:

berdasarkan bukti
- standard, neutral expression for “based on evidence”
- sounds natural and formal enough for academic/official use.
dari bukti = from evidence
- Grammatically OK, but slightly less idiomatic in this context.
- Could sound like the evidence is the source of something, rather than the basis for a judgment.

For assessment, decisions, conclusions, berdasarkan is the usual and best choice.